With the bunker's heavy metal lid dragged to one side, dank musty air rose up from the entrance, the forbidding gloom of the narrow steel-lined shaft below unbroken by the bright sunlight. It had taken seven months of searching to finally discover one of the underground bunkers that had enabled Hizballah to fire thousands of rockets into northern Israel last summer even under the pounding of Israeli air and ground operations. But any sense of exhilaration at the achievement was dampened by the nagging anxiety of claustrophobia.

"If we have to crawl when we're down there, I can't do it," said my colleague Ghaith Abdul Ahad.

The elaborate network of bunkers and fortified firing positions built over a six-year period in sealed-off valleys and hilltops throughout south Lebanon was key to Hizballah's ability to survive Israel's onslaught during last summer's month-long war. Israeli soldiers spoke of Hizballah fighters bursting out of the ground to loose off a rocket-propelled grenade before disappearing into the earth again. Israeli air crews hunted, often in vain, for the sources of Katyusha rocket fire, sometimes emanating from within a few hundred yards of the border. One bunker complex discovered and dynamited by Israeli troops a
week after the cease-fire reportedly covered more than a square mile and was fitted with hot and cold running water and air conditioning.

After the war, Hizballah had yielded security control of the area to a reinforced 12,000-strong U.N. peacekeeping force, but its bunkers remained elusive. They were hidden, their entrances well camouflaged, in the dense undergrowth of remote valleys often littered with unexploded Israeli ordnance. After several unsuccessful attempts to find one, last week I received map coordinates for two bunkers in a valley near the Christian border village of Alma Shaab. With the coordinates logged into a GPS device, Ghaith and I walked carefully along a track winding through blossom-scented orange orchards at the bottom of a steep-sided brush-covered valley. Snakes and lizards basking in the hot sun slithered from beneath our feet. But we kept our eyes open for cluster bombs, which have since August caused 224 casualties among Lebanese civilians and mine-clearing crews, which had used red spray paint to mark the location of each bomblet.

We almost missed the manhole cover beneath its layer
of dirt, dead leaves and twigs. Using metal footholds, I climbed down into the gloom below and saw with some relief that the tunnel at the bottom was larger than we had feared. We would have to crouch, but not crawl. It was still a tight squeeze as we inched cautiously along the dank silent passageway, which ran for about 20 feet before turning left and descending in a gradual slant. The rock sides of the tunnel were lined with a mesh of steel bars and girders. Huge brown spiders clinging to the walls watched the human intruders impassively.

A side tunnel was shielded with white steel plates and girders, which led into a small steel-walled chamber. The room, which was bare apart from two empty five-gallon water containers, must have been at least 100 feet underground,
and could probably have withstood a direct hit by a heavy bomb. A power cable along the walls linked several bare
bulbs, while a black plastic bag hanging from a hook contained the remnants of what last summer could have been fresh oranges or apples.

A few hundred yards away we found two rocket firing positions, one of them located in a 15-foot deep pit with reinforced concrete walls. A tunnel at the rear wall doglegged after a few feet into a small chamber lined with panels from wooden ammunition boxes where the rockets would have been stored. The second post consisted of a foot-thick reinforced concrete frame smothered with sandbags and camouflage netting and bolstered by Hesco blast protection walls. Even from a few yards up the hill, the position was all but invisible. And during the war, Hizballah gunners had tossed fire-retardant blankets over the launchers immediately after unleashing their rockets to hide the lingering heat signature from prowling Israeli aircraft.

The effort that went into building the fortifications in this valley alone had been extraordinary, and these were just three of dozens, possibly hundreds, scattered throughout southern Lebanon. The steel plates and girders, as well as the digging tools, sandbags and other equipment
had to be carried by hand up the steep slope from the valley floor and welded into place in the cramped claustrophobic tunnels. And Hizballah's engineers had managed to work undetected, despite near daily reconnaissance flights by Israeli jets and drones.

Both Hizballah and the Israeli military are still absorbing the lessons learned during last summer's conflict. But with continued speculation here over a possible "round two" between the militant Shi'ite group and Israel, it remains to be seen what fresh tricks Hizballah may still have up its sleeve.